0113. 路径总和 II.md

113. 路径总和 II

给你二叉树的根节点 root 和一个整数目标和 targetSum ，找出所有 从根节点到叶子节点 路径总和等于给定目标和的路径。

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/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} targetSum
 * @return {number[][]}
 */
var pathSum = function(root, targetSum) {
  if (!root) return []
  var result = []

  var hasPathSum = function(root, targetSum, history) {
    if (!root) return false
    if (!root.left && !root.right) {
      if (root.val === targetSum) {
        result.push(history)
        return true
      }
    } else {
      root.left && hasPathSum(root.left, targetSum - root.val, [...history, root.left.val])
      root.right && hasPathSum(root.right, targetSum - root.val, [...history, root.right.val])
    }
  };

  hasPathSum(root, targetSum, [root.val])

  return result
};